Tip Plates?
 

It the plates are big enough it becomes a triplane of small aspect ratio when in knife edge flight. It also is not very attractive as far as airplanes go.

As far as wings go a tip plate is a very inefficient wing. A slightly higher fuselage would put the area where it is already working for you.

The big TOC Ultimate bipe that Chip Hyde flew has outer struts between the wings that are very effective wings in knife edge since they have a nice wing type aspect ratio and the wings act to eliminate tip losses of the struts.

I am looking forward to reading about your experiment.

Tipplets
 

Hi BalsaBum; A slot will weaken the plates and maybe cause a whistle. My adjustable ones had three holes, one mounted the plate to be flush with the top of the wing (all plate area below the wing), one was in the center, and one caused the plate to be flush with the bottom of the wing (all plate area above the wing). I don't suppose you could tell the difference in any finer adjustments.

I just screwed on the approximate shape in the upper hole and then marked the plate to match the top of the wing. Then moved it to the lower hole and marked the bottom to match the underside of the tip rib. When you cut it out you have the perfect shape for an adjustable tipplet.

Tip Plates?
 

I fly a Balsa USA stingray with a Saito .72
flew it with and without the tipplets
ailerons more effective with them on
slower touch downs, espeacially with coupled elevator to flaperons will prop hang almost as good as my penknife
also have tipplets on a Hotdawg, much better flyer with them

Tip Plates?
 

------------ I fly a Balsa USA stingray with a Saito .72
flew it with and without the tipplets ailerons more effective with them on
slower touch downs, --------------

Easy to agree to here but when you say

----------- espeacially with coupled elevator to flaperons will prop hang almost as good as my penknife --------------

then I am not too sure. Doesn't coupling the elevator to flaperons pretty well make it difficult to establish that the tips are doing anything for you. Certainly prop hanging is a very difficult thing to evaluate. Since in prop hanging most of the roll moment is due to propwash across the wing/ailerons I am not too sure that tiplates do much for you in that respect.

----------- also have tipplets on a Hotdawg, much better flyer with them ---------

How does it fly better? With no ailerons I wouldn't expect any roll improvement. That just leaves pitch maneuvers and stall/landing characteristics. What did improve?

Tip Plates?
 

Hi Skypupmut; I too notice the improvement during flare-out and I attribute this to the ground-effect air-cushion being better contained under a wing with tipplets.

Ben; Either you're not a big fan of tipplets, or you just enjoy being the Devil's advocate. With flalperons coupled to elevator, when you flare by giving up elevator the flaperons go down, and full-span flaperons are more effective with tipplets that extend below the wing, just as the ailerons become more effective and noticably increase the roll rate.

Try 'em; you'll like 'em.

Tip Plates?
 

Ben; Think of tipplets as extending the wing span. They make the wing tip area more efficient, and for a wing with dihedral in place of ailerons, or a polyhedral wing, the tip area is going to become more efficient (more lift/less drag), and therefore the dihedral effect will be enhanced.

I've never tried tipplets on a rudder-only design, but they should increase roll stability if not roll rate, much as adding another rib bay to the wing tips.

Tip Plates?
 

Ralph, I tend to be a devil's advocate when performance claims are made. It is the result of years of flight and wind tunnel test where you make a change and then before it is considered by management you have to document the claimed results and show that they are repeatable. There is usually nothing worse than ancedotal reports because they can depend on the skill of the reporter, the weather, if a mosquito is biting you, if your significant other yelled at you or what you just ate for lunch.

The example of the tiplets is one of them. I know the limits of what tiplets/endplates, etc. can provide based on wind tunnel test I have been involved in. They can be quite beneficial in drag reduction when designed for that purpose. Another benefit when moved inboard a bit is the control of spanwise flow in transonic flight. The Russians were a fan of that approach, we never did use them in our designs perferring a less brute force approach to the problem.

When a flier says he put tiplets/endplates etc. on an airplane and it flew much better the question to ask is "how did it fly better"? In pitch, roll or yaw. Were angular rates increased or damping made better? Was the stall effected, how do you know?

Claims that are made for an aerodynamic device must be carefully considered. Modelers are basically honest but are as subject to the placebo effect as anyone else. They fly an airplane one weekend. Go home and put on tip plates and fly it the next weekend. It seems to fly better in all aspects. What is the most likely reason the airplane is performing better? Tip plates or the fact that the weather has changed so that the temperature is 20 degrees lower and the motor is running better, his headache is better and the flowers smell better and so on.

Most advances in model aerodynamics are made through cut and try and careful observation. Speed ships are measured by a stopwatch. Does the speed increase with a change? it is easy to determine with a dozen flights or so if a change is working. In the example of a freeflight contest power ship the stopwatch and several hundred flights can indicate if a change is helpful or harmful.

How many top world caliber freeflights (power, rubber, glider) use endplates, tiplets, etc.

How many top world caliber RC models in aerobatics use endplates, tiplets, etc?

How many top world caliber models in speed or indoor rubber duration use endplates, tiplets etc?

Are there any competitive areas where very competitive modelers would indeed sell their first born child to gain an advantage where any models have endplates, tiplets?

Not many, right? Why? Answer is they are not all that beneficial on a model scale.

Full scale gliders and cargo carriers use them but only after some performance improvements are carefully measured and documented but remember these are big airplanes.

In the area of handling qualities that are observable only from the ground with no instrumentation claims of performance improvements have to be made against what are the possible results from the changes being made. Tipplates, winglets, etc are by their very nature going to be limited in their effects on the airplane. In an earlier post I noted some ways that their effects could be noted.

There is a lot to be gained by a reasoned approach to modeling and experiments. It is not life, death, love or taxes but some care should be made when claiming improvements in model flight and the claimer of those results should expect to have his feet held to the fire.

Tip Plates?
 

Nicely written, Ben, and you are absolutely right about anecdotal evidence.. .

Let's wait for the results of Bentgear's and BalsaBum's experiments with tiplets, before we decide they aren't beneficial. If three of us find them beneficial, by our observations, will you try them yourself?

Andy Lennon likes 'em. Of course he used them on a design where the goal was a high-efficiency model.

Competitors tend to use what the competition uses, so as not to be different with negative results. That's why pattern planes look very much alike, at any given time.

If one competitive pattern flier uses tiplets at some point, you can bet that most of the other competitors will adopt them too, just in case there might be some advantage.

I would think pylon racers could benefit from using tiplets, but I don't know enough about the rules. If they are classed by span, then tipplets would provide an advantage and I would guess they would not be allowed.

Tip Plates
 

Is this thread closed? I don't see it in the forum index.

Tip Plates?
 

They never close Ralph, they just keep getting pushed down the stack. Have not been able to do any testing yet between crappy weather and trying to get a cap flying.
Ed M.

Tip Plates?
 

I don't know that this will add much to the discussion but the wingtip vortices are only present when an a/c is in the air. They will disapate upon touchdown; I have seen this phenominum only a couple of times.

Tip Plates?
 

Hi Hal;

Yeah, I've noticed that they're no problem once you land.

And you can see them on a moist, foggy day. Sort of twirly.